1. Field of the Invention
This invention pertains generally to switches that signal a specified condition of an electric power apparatus and, more particularly, to switches that include a sensor employing mechanical or non-contact actuation by the apparatus, and to electric power apparatus employing such a switch.
2. Background Information
Circuit breakers for telecommunication systems typically are smaller than circuit breakers associated with power distribution networks. A typical telecommunication system circuit breaker measures 2.5 inches high by 2.0 inches long by 0.75 inch thick, when the circuit breaker is viewed with the operating handle extending horizontally and moving in a vertical arc. While having a reduced size, the telecommunication system circuit breaker must still accommodate the various components and devices (e.g., separable contacts; trip device; operating mechanism) associated with larger circuit breakers. Thus, while the conventional components of a telecommunication system circuit breaker may not be unique, the necessity of having a reduced size requires specialized configurations and robust components that are different than power distribution circuit breakers. This is especially true where the telecommunication system circuit breakers are used in environments wherein the circuit breaker may be expected to operate for over 10,000 operating cycles and 50 tripping cycles; however, the reduced size telecommunication system circuit breakers are typically limited to a current rating of 30 amps.
The telecommunication system circuit breaker is structured to be disposed in a multi-level rack. The rack has multiple telecommunication system circuit breakers on each level. The rack, preferably, has a spacing between the levels of 1.75 inches; however, the current structure of telecommunication system circuit breakers, as noted above, have a height of 2.5 inches. As such, users have been required to adapt the multi-level rack to accommodate the taller telecommunication system circuit breakers.
Circuit breakers disposed on the rack may be coupled to associated circuits. As such, if the current is interrupted in a first circuit, either due to the circuit breaker tripping or due to a user manually interrupting the circuit, it is sometimes desirable to interrupt the current on an associated second circuit. In the prior art, a common trip bar was structured to trip two adjacent circuit breakers. That is, a single trip bar extended across two circuit breakers and, if an over current condition occurred in either circuit, the actuation of the trip device caused the trip bar to rotate thereby tripping both circuit breakers. In smaller circuit breakers which have a low trip force, the use of a common trip bar is not feasible.
Thus, while existing telecommunication system circuit breakers are small, there is still a need for telecommunication system circuit breakers having a reduced height, especially a telecommunication system circuit breaker having a height of about, or less than, 1.75 inches; the preferred spacing between levels on the rack. As the size of the telecommunication system circuit breakers are reduced further, the need for robust, yet small, components which operate in a reduced space is increased.
Electric power apparatus, such as circuit breakers, transfer switches, network protectors and the like, often are equipped with auxiliary switches that provide signals indicating certain conditions within the apparatus. Such auxiliary switches indicate whether the separable contacts are open or closed and/or whether the device has been tripped open. The signals generated by the switches can be used for communicating the condition to a remote location.
Typically, the auxiliary switches are mechanically actuated, usually through physical contact with, or by a linkage to, the operating mechanism that opens and closes the separable contacts. Many electric power apparatus have sufficient room inside a housing to accommodate the auxiliary switches, or the housing includes a compartment containing the switch. Some electric power apparatus are physically too small or otherwise do not have sufficient space available for the auxiliary switch within the housing. In such circumstances, these mechanically actuated switches can be contained within their own housing mounted on the outside of the apparatus housing. However, this requires an opening in the housing for the mechanical linkage.
U.S. patent application Publication No. 2004/0130217 discloses a non-contact auxiliary switch and electric power apparatus incorporating the same. The auxiliary switch includes a non-contact sensor, such as a Hall effect device, that is switched by the condition of a magnetic field. The magnetic field condition is effected by a moving piece or movable contact indicator coupled to and moved by the operating mechanism. This movable contact indicator is pivoted about a mounting pin that moves between open and closed positions with the separable contacts of the electric power apparatus. A magnet may be attached to the movable contact indicator or the movable contact indicator can be magnetized to form the magnet. Alternatively, the movable contact indicator can intercept or not intercept a magnetic field produced by a fixed magnet spaced from the sensor. The Hall effect device may be mounted on the outside of the non-magnetically permeable housing of the electric power apparatus or inside if there is sufficient room. In either case, no mechanical coupling is required for the sensor.
There is room for improvement in auxiliary switches.
There is also room for improvement in electric power apparatus including auxiliary switches.
There is further room for improvement in circuit breakers, such as a telecommunication system circuit breaker, having a reduced size but including an auxiliary switch.